1. Field of Invention
The present invention relates in general to detecting systems for detecting operation condition of a direct current motor, and more particularly to detecting systems of a type that detects abrasion of a brush of a direct current motor employed as a power generator in electric vehicles, hybrid type vehicles and the like.
2. Description of Related Art
In order to detect abrasion of a brush of a DC motor, Laid-Open Japanese Patent Application (Tokkaihei) 5-304746 discloses a system that issues an alarm when the brush is worn down by a certain degree. That is, the system comprises a detection contact that is connected to the brush to move therewith. When, due to abrasion of the brush, the detection contact is brought into contact with a receiving contact, an alarm circuit is closed thereby to generate an alarm sound. Thus, the abrasion of the brush is automatically detected and a necessary measure can be adopted in advance. However, due to its inherent construction, the system of the published application has failed to exhibit a satisfied performance.